Micropositioning mechanism



y 9, 1967 J. GUERNET 3,318,593

MI CROPOS ITIONING MECHANI SM Filed Dec. 15, 1964 2 Sheets-Shea; 1

y 9, 1967 J. GUERNET 3,318,593

MICROPOSITIONING MECHANISM Filed Dec. 15, 1964. 2 Sheets-Sheet 2 UnitedStates Patent Ofiice 3,318,593 Patented May 9, 1967 3,318,593MICROPOSITIONING MECHANISM Jacques Guernet, Courbevoie, France, assignorto C.A.M.E.C.A.Compagnie dApplications Mechaniques a IElectronique auCinema et a IAtomistique, a

corporation of France Filed Dec. 15, 1964, Ser. No. 418,513 Claimspriority, application France, Dec. 17, 1963, 957,394 6 Claims. (Cl.269-60) The present invention relates to mechanism for providing smalldisplacements of an object in a given direction.

According to the invention there is provided a mechanism for providinglimited displacements of a stage memher in a given direction, comprisinga rigid support, first and second coplanar and parallel elastic strips,extending in respective planes normal to said direction and having theirends rigidly connected to said support and to said member respectively,the respective intermediate portions of said first strips being rigidlyconnected to a rigid body, rigidly connected by further parallel elasticstrips, directed along said given direction, to said support and memberand means for pivoting said body about the line of intersection of theplanes respectively tangent to said first strips and said furtherstrips.

The invention is particularly applicable to the displacement of a stage,such as a microscope stage.

For a better understanding of the invention and to show how the same maybe carried into effect, reference will be made to the drawing,accompanying the following description and in which:

FIG. 1 shows in section one embodiment of an arrangement according tothe invention, given by way of example;

FIG. 2 shows the same embodiment in perspective;

FIG. 3 shows a detail of FIG. 1;

FIGS. 4 and 5 show in cross-section one example of application of theinvention; and

'FIG. 6 shows a detail of FIG. 5.

FIGS. 1 and 2 show a fixed frame 1 generally shaped as a corner iron andincluding a vertical, plane and solid plate 301 having two lateralprojections, as shown in FIG. 2, which carry on their upper endshorizontal elastic strips '16 and 17. The strips may be mounted, forinstance, by means of screws.

Strips 16 are inset or screwed at their intermediate portions in a solidand substantially horizontal bar 303, which is in turn fixed to thevertical wall of plate 301, by vertical elastic strips 306, fixed attheir ends to parts 301 and 303, respectively.

At their free ends, opposite to plate 301, strips 16 and 17 are fixed toa solid vertical plate 304, which is also fixed to bar 303 by furthervertical strip 306.

An arm 302, solid with or fixed to bar 303, may be moved by means of ascrew, screwed in plate 301 and terminated with a knurled knob 7, toadjust the position of bar 303.

The operation of the arrangement will be understood with reference toFIG. 3 which shows, at an enlarged scale, how plate 301 is fixed to bar303.

As the screw actuated by knob 7 presses against arm 302 in the directionof the arrow, arm 302 tilts to the right. Strips 16, 17 and 306 areelastically distorted and, because their respective free lengths aresmall as compared to their total length, since they are fixed to parts303 and 301, it can be shown that their distortion is such that theintersection line M of planes respectively tangential to strips 306 attheir fixation points on plate 301 and to strips 16 at their fixationpoints on bar 303 remains stationary.

Thus the system of strips 16 and 17 may be considered as forming thesides of an articulated parallelogram whose sides 301 and 304 retain afixed direction.

Side 304 thus moves in a direction parallel to itself. Since thedisplacements are of small extent, everything happens as though it wereto slide along itself.

The invention may advantageously be applied for producing verticaldisplacements of a specimen carrying stage, designed for the examinationof a small object by means of a vertical axis electron optics system.Such vertical movements, which are made when adjusting the instrument,are always of small amplitude.

In order to explore the various areas of an object, it is necessary tobe able to move the object holder in two horizontal directions Ox and0y. In addition, in spite of the fact that the arrangement is kept underhigh vacuum, all controls have to be extremely sensitive and accurate,and the object must be capable of being positioned to within 1;.

FIGS. 4 and 5 show, respectively in section through planes BB and AA,one embodiment of such an object holder or stage.

The stage system as a whole is located in a frame 2 which, once theevacuation has taken place, is in a fixed position. The stage has to bemoved in three directions Ox, 0y and Oz forming a trirectangulartrihedron with respect to this frame, the displacement along Oz takingplace as just described.

In order to make displacements along Ox possible, the base of support 1is provided with two rods 4 and 5 extending in the direction Ox. Rod 4is slidably mounted in bearings 3 and rod 5 is slidably mounted in abearing sleeve 6.

Bearings 3 are fixed to the bottom of frame 2. Sleeve 6 is, as shown inFIG. 6 in section along line C-C' of FIG. 5, mounted on the bottom offrame 2 with a certain degree of freedom. To this end, sleeve 6 is fixedto the bottom of frame 2 by means of a screw 30 whose head 29 bearsagainst a cup 9 located in a cavity formed in the bottom of frame 2.Between frame 2 and sleeve 6 are placed two balls 7 and 8 sothat theconnection acts some, what as a knee joint.

This three point mounting makes it possible to avoid any detrimentalstrain.

Since the assembly operates in vacuum, bars 3 and 5 are made ofstainless steel and slide in plastic bearing rings.

The displacement in the direction Ox as obtained by means of a screw 25driven by a knurled knob X.

The displacement along direction Oy is achieved in a similar manner. Tothis end the arrangement comprises a'solid-rnember 15, which plays thesame part as member 304 of FIGS. 1 to 4 and is'supported in the samemanner. Member 15 carries rod 13 by means of two bearings (not shown)and similar to bearings 3. "Rod 13 supports a stage 12. Stage 12 is alsofixed to member 15 by means of a further rod 14 mounted in a furthersleeve 27, entirely similar to and mounted as sleeve 6. Stage 12 isdisplaced along direction Oy by sliding on rods 13 and 14 by means of 'ascrew 21, driven by a knurled knob Y connected thereto by means offlexible connections 22 and 23.

The displacement along direction Oz takes place as already described. Itis performed by means of a gear 20 controlling a screw 19 acting on anarm 18, similar to the arm 302 of FIGS. 1 to 4. Gear 20 is actuated bymeans of a driving knurled knob Z.

Of course the invention is not limited to the embodiments described andshown which were given solely by way of example.

What is claimed is:

1. A mechanism for providing limited displacements of a member in agiven direction, comprising: a rigid support; first coplanar andparallel elastic strips; second coplanar and parallel elastic stripsextending in a plane parallel to said first strips; said stripsextending in respective planes normal to said direction and having endsrigidly connected to said support and to said member respectively andhaving respective intermediate portions; a rigid bar rigidly connectedto said intermediate portions of said first strips; first and secondfurther parallel elastic strips directed along said given direction andrigidly connecting said bar to said support and said memberrespectively; and means for pivoting said bar about the line ofintersection of the planes respectively tangent to said first strips andsaid first further strips.

2. A mechanism for providing limited displacements of a member in agiven direction, comprising: a rigid support; a pair of first coplanarand parallel elastic strips; a pair of second coplanar and parallelelastic strips extending in a plane parallel to saidfirst strips; saidstrips extending normally to said direction and having ends rigidlyconnected to said support and to said member respectively and havingrespective intermediate portions; a rigid bar rigidly connected to saidintermediate portions of said first strips; first and second furtherparallel elastic strips directed normally to the plane of said firststrips and rigidly connecting said bar to said support and said memberrespectively; and means for pivoting said bar about the line ofintersection of the planes respectively tangent to said first strips andsaid first further strips.

7 3. An object carrier st-age arrangement including a mechanism forproviding limited displacements of said stage in a first direction andthe respective displacements thereof in a second and a third mutuallyperpendicular directions perpendicular to said first direction,comprising in combination: a rigid support; a stage carrier member;first coplanar and parallel elastic strips; second coplanar and parallelelastic strips extending in a plane parallel to said first strips; saidstrips extending in respective planes normal to said first direction andhaving ends rigidly connected to said support and to said stage carriermember respectively and having respective intermediate portions; a rigidbar rigidly connected to said intermediate portions of said firststrips; first and second further parallel elastic strips directed alongsaid first direction and rigidly connecting said bar to said support andsaid stage carrier member respectively; means for pivoting said barabout the line of intersection of the planes respectively tangent tosaidfirst strips and said first further strips; a fixed frame; bearingmeans solid with said frame and supporting ,said support slidably insaid second direction; further hear:

ing means solid with said stage carrier member and supporting said stageslidably in said third direction; and means for displacing said supportand said stage in said second and third directions respectively.

I 4. An object carrier stage arrangement including a mechanism forproviding limited displacements of said stage in a given verticaldirection, and the respective displacements thereof in a second and athird mutually perpendicular horizontal directions comprising incombination: a rigid support; a rigid stage carrier member; firstcoplanar and parallel elastic strips, second coplanar and parallelelastic strips extending in a plane parallel to said V first strips;said strips extending in respective planes normal to said verticaldirection and having ends rigidly connected to said support and to saidmember respectively and having respective intermediate portions; a rigidbar rigidly connected to said intermediate portions of said firststrips; first and second further parallel elastic strips directed alongsaid vertical direction and rigidly connecting said bar to said supportand said stage carrier member respectively; means for pivoting said barabout the line of intersection of the planes respectively tangent tosaid first strips and said first further strips; a fixed frame; a tablecarrying said rigid support; a first and a second rigid rod carried bysaid table, extending in said second hori: zon-tal direction; two firstbearings and a first sleeve, carried by said frame, said first andsecond rods'being slidably mounted respectively in said first bearingsand in said first sleeve; a stage having a third and a fourth rodextending in said third direction; two second bearings and a secondparallel elastic strips extending in a plane parallel to said firststrips; said strips extending in respective planes normal to said firstdirection and having ends rigidly connected to said support and to saidmember respectively and having'respective intermediateportions; a rigidbar rigidly connected to said intermediate portions of said firststrips; first and secondfurther parallel elastic strips directed alongsaid first given direction and rigidly connecting said bar to saidsupport and said stage member respectively; means for pivoting said barabout the line of intersection of the planes respectively tangent tosaidfirst strips and said first further strips; a fixed frame; a tablecarrying said rigid support, a first and a second rigid rod carried bysaid table, extending in said second horizontal direction; two firstbearings carried by said frame and a-first sleeve, non-rigidly mountedon said frame, said first and second rods being slidably mountedrespectively .in said first bearings and in said, first sleeve; a stagecarrying a third and a fourth rod extending in said third direction;

two second bearings solid with said stage 'carrierme mber and a secondsleeve non-rigidly mounted on said member;

said third and said fourth rods, being slidably mounted in said secondbearings and in said second sleeve.

6. A system as claimed in claim 5,'comprising screws connecting saidsleeves respectively to said frame and member and balls interposedbetween said sleeves and said .frame and member respectively.

RICHARD EABNESY, 111., Primary Examiner.

1. A MECHANISM FOR PROVIDING LIMITED DISPLACEMENTS OF A MEMBER IN AGIVEN DIRECTION, COMPRISING: A RIGID SUPPORT; FIRST COPLANAR ANDPARALLEL ELASTIC STRIPS; SECOND COPLANAR AND PARALLEL ELASTIC STRIPSEXTENDING IN A PLANE PARALLEL TO SAID FIRST STRIPS; SAID STRIPSEXTENDING IN RESPECTIVE PLANES NORMAL TO SAID DIRECTION AND HAVING ENDSRIGIDLY CONNECTED TO SAID SUPPORT AND TO SAID MEMBER RESPECTIVELY ANDHAVING RESPECTIVE INTERMEDIATE PORTIONS; A RIGID BAR RIGIDLY CONNECTEDTO SAID INTERMEDIATE PORTIONS OF SAID FIRST STRIPS; FIRST AND SECONDFURTHER PARALLEL ELASTIC STRIPS DIRECTED ALONG SAID GIVEN DIRECTION ANDRIGIDLY CONNECTING SAID BAR TO SAID SUPPORT AND SAID MEMBERRESPECTIVELY; AND MEANS FOR PIVOTING SAID BAR ABOUT THE LINE OFINTERSECTION OF THE PLANES RESPECTIVELY TANGENT TO SAID FIRST STRIPS ANDSAID FIRST FURTHER STRIPS.